form does not generate $_POST request

According to the WP codex, the submit_button in WP will generate the HTML code for the submit button. (See example in Codex https://codex.wordpress.org/Function_Reference/submit_button ).

So, additional info needed: what is the generated page code look like for the form? (from the Page Source). Is any code being generated?

But that’s not your problem. The problem is the ‘Required’ parameter of the statement; it is invalid. Should be

required="Enable" >

Closing “>” is missing also.

Sometimes, looking at the generated page code will help you find the problem.